It’s ironic that it often seems easier for perpetrators of genocide to admit what they are doing than for others to do so. The Islamic State has told us it wants to destroy Christianity and kill Christians and other minority groups, and has acted on those words, exterminating and enslaving, destroying every vestige of Christianity they can find.

But the State Department hasn’t called this genocide. It faces a March 17 deadline set by Congress by which to make a determination. A failure to term this genocide will obscure what has happened and encourage its repetition and relativize its meaning.

Twice in the last century, the United States looked the other way as genocide unfolded. During World War II, America turned its back on the “voyage of the damned,” sending its majority-Jewish passengers back to war-torn Europe, many to their deaths. And an infamous memo by Assistant Secretary of State Breckinridge Long listed how to keep those at risk out of the United States, by delaying their visas.

More recently, the lack of will to call what happened in Rwanda genocide stands as a terrible blight on the Clinton administration and its State Department, which used the term internally, but refused to use it publicly.

This time, America still has a chance to do the right thing and to make a difference. What is required is our moral leadership.

Mass graves, orange jumpsuits, beheadings, kidnapping, rape, slavery, dispossession, expulsion and the destruction of every sign of Christianity from ISIS’s controlled territories have reminded us of our moral duty to prevent genocide as it occurs, not simply decry it afterwards.

The United Nations Convention on Genocide defines genocide as killing and certain other acts “committed with intent to destroy, in whole or in part, a national, ethnical, racial or religious group.”

ISIS’ actions against Christians and other minorities unquestionably meet that definition. In the case of Christians alone, the group has assassinated church leaders; conducted mass murders and burials; tortured and kidnapped individuals; conducted campaigns of forced marriage, sexual slavery, pedophilia and rape, destroyed churches, monasteries, cemeteries, and artifacts; raped Christian girls and women; and engaged in forcible conversion to Islam. The lucky ones fled to squalid camps or temporary shelters. Communities were shattered, and a culture and way of life stands on the brink of extinction.

ISIS hasn’t been shy about its intent. It publicly takes credit for the murder of Christians and other minorities, while expressing a desire to eliminate these communities from the caliphate.

There is no lack of clarity in such a statement, and we would have to strain to miss the plain meaning of their words – backed up by their actions.

This is what genocide looks like.

A bipartisan coalition of presidential candidates and world leaders agree. Hillary Clinton, Ted Cruz, John Kasich and Marco Rubio have all called what is happening in the Middle East genocide against Christians. Pope Francis did so as well, last July.

The European Parliament has called it by its rightful name in a historic step, especially in light of the continent’s 20th century experience. It is the first time the European Union has recognized an ongoing situation as genocide and called it to the world’s attention.

Also moved by the evidence has been the United States Commission on International Religious Freedom (USCIRF), established by Congress, as well as groups like Genocide Watch and 50 or so members of the International Association of Genocide Scholars.

A House resolution by Rep. Jeff Fortenberry, R-Neb., to declare the “atrocities against Christians and other ethnic and religious minorities” genocide passed the House unanimously on March 14.

The State Department has a moral obligation to name this formally – following the lead of Europe, genocide scholars, Pope Francis and the USCIRF.

If America can’t call this what it really is, if we say “it’s bad, but not that bad,” how can we credibly demand that this extermination – or others in the future – end?

For “never again” to have meaning, action must be taken now.

Secretary of State John Kerry said in 2014, “ISIL’s campaign of terror against the innocent, including Yazidi and Christian minorities, and its grotesque and targeted acts of violence bear all the warning signs and hallmarks of genocide.”

He was right. And things have gotten worse, not better.

Now, the State Department has just two weeks to say it formally as time is running out: not simply because its credibility is on the line, which it is, but because part of America’s greatness is its international leadership role in protecting the defenseless. We cannot abrogate that role.

For those minorities being targeted by ISIS, and for Christianity in this region, there will be no second chance.

Carl Anderson is CEO of the Knights of Columbus, a New York Times bestselling author and a former member of the United States Commission on Civil Rights.The Most Rev. Sarhad Y. Jammo is a native of Iraq and has served as the Bishop of the Chaldean Catholic Eparchy of St. Peter the Apostle of the Western USA since 2002.